static methods in detail

[budsy remo]

I have 3 questions related to the following program:-

class Y
{
}
class Xyz
{
    public static void main(String[] args)
    {
        int x=0;
        System.out.println(x);
        Y y1=new Y();
        Xyz x1=new Xyz();
        S1 st=new S1();//this will give me an error
    }

    class S1
    {
    }
}

My question starts from the eight'th line ....
1.if we cannot access non static variables why does the static method main lets me make a variable x?
2.i get it that i cannot make an instance variable of S1 but then why can i make an instance variable of Y?

I am sorry if the questions are too stupid but i think it's best to have answers for the language you love.

[fred rosenberger]

Your code won't compile at all, so it's hard to answer your questions... There is an extra '}' at the end, and you don't initialize 'x'.

If you correct those two errors, it compiles and runs just fine.

and for question 1, the answer is because it is not a non-static variable.

[Rob Spoor]

Please keep your indentation when pasting code next time. I've added some and it immediately shows that class S1 is a non-static nested class inside class Xyz. I think Fred missed that (because of the lack of indentation), because there is no extra }.

budsy remo wrote:1.if we cannot access non static variables why does the static method main lets me make a variable x?

You can't access non static fields. Local variables declared inside the method itself are always accessible inside the method.

2.i get it that i cannot make an instance variable of S1 but then why can i make an instance variable of Y?

Class Y is a top-level class. Class S1 is, as I said before, a non-static nested class inside class Xyz (a.k.a. an inner class). Because it's nested the same rules for fields apply - you need an instance to create instances of this class:

S1 st = x1.new S1();

[fred rosenberger]

yup...totally missed it was an inner-class.

[Jesper de Jong]

For detailed background information, see: Understanding Instance and Class Members.

[budsy remo]

thanks a million Rob Spoor ,didn't know that we can actually make instances of an inner class through that syntax . Thanks to others too for answering .Will give some more study .